A major challenge in obtaining large quantities of algal biomass at a very low cost is to attain a continuous and stable production of algae. To achieve this, the algae have to be stably cultivated round the year in open ponds at a sufficiently high density. However, algae when cultivated in open ponds are prone to numerous abiotic and biotic stresses, which lead to frequent culture crashes and productivity losses. Abiotic stress can be taken care to a large extent through bio prospecting, screening and selection of the right kind of algal strains for a particular geographic location and season. Managing contaminants in open ponds along with maintaining high productivity of algae for successful biofuel production is very difficult.
Grazers and contaminating organisms are a major concern in the cultivation of algae. Ciliates, dinoflagellates, rotifers, diatoms, filamentous and unicellular cyanobacteria, flagellates, etc, either feed or compete with the algae for nutrients, resulting in reduced production of the algal biomass. Various chemicals are known, which can be used to kill the grazers and the contaminating organisms, however, these chemicals also have a deleterious effect on the algal growth.
Therefore, there is felt a need for large scale production of algae that mitigates the drawbacks mentioned hereinabove.